Menu Master is what's known as a "haxie" that allows you to change or remove menu shortcut keys in any application.
Note that haxies are technically hacking your OS X system and should be used with care as they can make fundamental changes to the way it works which can be hard to reverse. In addition, there's no real need to use Menu Master in Snow Leopard anyway. You can go to your System Preferences, select Keyboard Shortcuts and Application Shortcuts and easily change Menu Items without the need for a haxie like Menu Master.
Menu Master is slightly faster however. And it offers you the possibility to leave a Menu item completely bank with no command unlike System Preferences. It's also a bit more flexible than System Preferences because it allows you to define almost any command you want to
However, there's no real need for Menu Master although if you want full control over Menu commands, you may find it useful.
- Fixed a compile bug that prevented Menu Master from loading in PowerPC applications (like Word 2004).